How is the credit limit calculated?

[vivtho]

My airline has a value of over 110million (Assets-loans).  I own three aircraft with a combined value of 84 million.  Despite this, the maximum loan I am allowed to take out is 18.6 million.

Any idea why this is?

[Jake43]

A vast majority of it is based on how much loans you have taken out. For example, I have roughly 60 million in assets (Cash + Planes) with no loans out. Therefore i could take 22 million of unsecured. However, had I had even 5 million in loans it would significantly decrease the amount i could borrow, maybe even to zero.

So, even if you are economically sound, you won't be able to take out loans with other loans out. You will either need to increase you assets, or pay off the previous loans.